There is significant and increasing interest in utilizing direct methanol fuel cells (DMFCs) for portable power applications. Currently, most attention is focused on DMFC sub-watt power systems that are relatively simple. However, more sophisticated systems, providing more than several watts of power, can provide higher power densities. Stack designs for such systems mirror conventional hydrogen fuel cell approaches, i.e., multiple bipolar plates aligned in series with internal manifolds for reactant delivery and removal. However, certain features differentiate the stack design of this invention from its hydrogen and methanol predecessors. Some features provide improved performance and stability for operation with dilute liquid methanol feed and non-humidified reactant air, low reactant pressure and low air-supply stoichiometry. Other features improve ease of fabrication, durability of the components, uniformity of cell operation within the stack, and enable reduction in stack size and weight.